1/* 2 * Copyright (C) 1999, 2000, 2002 Niibe Yutaka 3 * Copyright (C) 2003 - 2008 Paul Mundt 4 * 5 * This file is subject to the terms and conditions of the GNU General Public 6 * License. See the file "COPYING" in the main directory of this archive 7 * for more details. 8 * 9 */ 10 11! NOTE: 12! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address 13! to be jumped is too far, but it causes illegal slot exception. 14 15/* 16 * entry.S contains the system-call and fault low-level handling routines. 17 * This also contains the timer-interrupt handler, as well as all interrupts 18 * and faults that can result in a task-switch. 19 * 20 * NOTE: This code handles signal-recognition, which happens every time 21 * after a timer-interrupt and after each system call. 22 * 23 * NOTE: This code uses a convention that instructions in the delay slot 24 * of a transfer-control instruction are indented by an extra space, thus: 25 * 26 * jmp @k0 ! control-transfer instruction 27 * ldc k1, ssr ! delay slot 28 * 29 * Stack layout in 'ret_from_syscall': 30 * ptrace needs to have all regs on the stack. 31 * if the order here is changed, it needs to be 32 * updated in ptrace.c and ptrace.h 33 * 34 * r0 35 * ... 36 * r15 = stack pointer 37 * spc 38 * pr 39 * ssr 40 * gbr 41 * mach 42 * macl 43 * syscall # 44 * 45 */ 46#include <asm/dwarf.h> 47 48#if defined(CONFIG_PREEMPT) 49# define preempt_stop() cli ; TRACE_IRQS_OFF 50#else 51# define preempt_stop() 52# define resume_kernel __restore_all 53#endif 54 55 56 .align 2 57ENTRY(exception_error) 58 ! 59 TRACE_IRQS_ON 60 sti 61 mov.l 1f, r0 62 jmp @r0 63 nop 64 65 .align 2 661: .long do_exception_error 67 68 .align 2 69ret_from_exception: 70 CFI_STARTPROC simple 71 CFI_DEF_CFA r14, 0 72 CFI_REL_OFFSET 17, 64 73 CFI_REL_OFFSET 15, 60 74 CFI_REL_OFFSET 14, 56 75 CFI_REL_OFFSET 13, 52 76 CFI_REL_OFFSET 12, 48 77 CFI_REL_OFFSET 11, 44 78 CFI_REL_OFFSET 10, 40 79 CFI_REL_OFFSET 9, 36 80 CFI_REL_OFFSET 8, 32 81 preempt_stop() 82ENTRY(ret_from_irq) 83 ! 84 mov #OFF_SR, r0 85 mov.l @(r0,r15), r0 ! get status register 86 shll r0 87 shll r0 ! kernel space? 88 get_current_thread_info r8, r0 89 bt resume_kernel ! Yes, it's from kernel, go back soon 90 91#ifdef CONFIG_PREEMPT 92 bra resume_userspace 93 nop 94ENTRY(resume_kernel) 95 cli 96 TRACE_IRQS_OFF 97 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count 98 tst r0, r0 99 bf noresched 100need_resched: 101 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 102 tst #_TIF_NEED_RESCHED, r0 ! need_resched set? 103 bt noresched 104 105 mov #OFF_SR, r0 106 mov.l @(r0,r15), r0 ! get status register 107 shlr r0 108 and #(0xf0>>1), r0 ! interrupts off (exception path)? 109 cmp/eq #(0xf0>>1), r0 110 bt noresched 111 mov.l 3f, r0 112 jsr @r0 ! call preempt_schedule_irq 113 nop 114 bra need_resched 115 nop 116 117noresched: 118 bra __restore_all 119 nop 120 121 .align 2 1221: .long PREEMPT_ACTIVE 1232: .long schedule 1243: .long preempt_schedule_irq 125#endif 126 127ENTRY(resume_userspace) 128 ! r8: current_thread_info 129 cli 130 TRACE_IRQS_OFF 131 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 132 tst #(_TIF_WORK_MASK & 0xff), r0 133 bt/s __restore_all 134 tst #_TIF_NEED_RESCHED, r0 135 136 .align 2 137work_pending: 138 ! r0: current_thread_info->flags 139 ! r8: current_thread_info 140 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 141 bf/s work_resched 142 tst #_TIF_SIGPENDING, r0 143work_notifysig: 144 bt/s __restore_all 145 mov r15, r4 146 mov r12, r5 ! set arg1(save_r0) 147 mov r0, r6 148 mov.l 2f, r1 149 mov.l 3f, r0 150 jmp @r1 151 lds r0, pr 152work_resched: 153 mov.l 1f, r1 154 jsr @r1 ! schedule 155 nop 156 cli 157 TRACE_IRQS_OFF 158 ! 159 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 160 tst #(_TIF_WORK_MASK & 0xff), r0 161 bt __restore_all 162 bra work_pending 163 tst #_TIF_NEED_RESCHED, r0 164 165 .align 2 1661: .long schedule 1672: .long do_notify_resume 1683: .long resume_userspace 169 170 .align 2 171syscall_exit_work: 172 ! r0: current_thread_info->flags 173 ! r8: current_thread_info 174 tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0 175 bt/s work_pending 176 tst #_TIF_NEED_RESCHED, r0 177 TRACE_IRQS_ON 178 sti 179 mov r15, r4 180 mov.l 8f, r0 ! do_syscall_trace_leave 181 jsr @r0 182 nop 183 bra resume_userspace 184 nop 185 186 .align 2 187syscall_trace_entry: 188 ! Yes it is traced. 189 mov r15, r4 190 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies 191 jsr @r11 ! superior (will chomp R[0-7]) 192 nop 193 mov.l r0, @(OFF_R0,r15) ! Save return value 194 ! Reload R0-R4 from kernel stack, where the 195 ! parent may have modified them using 196 ! ptrace(POKEUSR). (Note that R0-R2 are 197 ! used by the system call handler directly 198 ! from the kernel stack anyway, so don't need 199 ! to be reloaded here.) This allows the parent 200 ! to rewrite system calls and args on the fly. 201 mov.l @(OFF_R4,r15), r4 ! arg0 202 mov.l @(OFF_R5,r15), r5 203 mov.l @(OFF_R6,r15), r6 204 mov.l @(OFF_R7,r15), r7 ! arg3 205 mov.l @(OFF_R3,r15), r3 ! syscall_nr 206 ! 207 mov.l 2f, r10 ! Number of syscalls 208 cmp/hs r10, r3 209 bf syscall_call 210 mov #-ENOSYS, r0 211 bra syscall_exit 212 mov.l r0, @(OFF_R0,r15) ! Return value 213 214__restore_all: 215 mov #OFF_SR, r0 216 mov.l @(r0,r15), r0 ! get status register 217 218 shlr2 r0 219 and #0x3c, r0 220 cmp/eq #0x3c, r0 221 bt 1f 222 TRACE_IRQS_ON 223 bra 2f 224 nop 2251: 226 TRACE_IRQS_OFF 2272: 228 mov.l 3f, r0 229 jmp @r0 230 nop 231 232 .align 2 2333: .long restore_all 234 235 .align 2 236syscall_badsys: ! Bad syscall number 237 get_current_thread_info r8, r0 238 mov #-ENOSYS, r0 239 bra resume_userspace 240 mov.l r0, @(OFF_R0,r15) ! Return value 241 242/* 243 * The main debug trap handler. 244 * 245 * r8=TRA (not the trap number!) 246 * 247 * Note: This assumes that the trapa value is left in its original 248 * form (without the shlr2 shift) so the calculation for the jump 249 * call table offset remains a simple in place mask. 250 */ 251debug_trap: 252 mov r8, r0 253 and #(0xf << 2), r0 254 mov.l 1f, r8 255 add r0, r8 256 mov.l @r8, r8 257 jsr @r8 258 nop 259 bra __restore_all 260 nop 261 CFI_ENDPROC 262 263 .align 2 2641: .long debug_trap_table 265 266/* 267 * Syscall interface: 268 * 269 * Syscall #: R3 270 * Arguments #0 to #3: R4--R7 271 * Arguments #4 to #6: R0, R1, R2 272 * TRA: (number of arguments + ABI revision) x 4 273 * 274 * This code also handles delegating other traps to the BIOS/gdb stub 275 * according to: 276 * 277 * Trap number 278 * (TRA>>2) Purpose 279 * -------- ------- 280 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). 281 * 0x10-0x1f general SH-3/4 syscall ABI. 282 * 0x20-0x2f syscall ABI for SH-2 parts. 283 * 0x30-0x3f debug traps used by the kernel. 284 * 0x40-0xff Not supported by all parts, so left unhandled. 285 * 286 * Note: When we're first called, the TRA value must be shifted 287 * right 2 bits in order to get the value that was used as the "trapa" 288 * argument. 289 */ 290 291 .align 2 292 .globl ret_from_fork 293ret_from_fork: 294 mov.l 1f, r8 295 jsr @r8 296 mov r0, r4 297 bra syscall_exit 298 nop 299 .align 2 3001: .long schedule_tail 301 302/* 303 * The poorly named main trapa decode and dispatch routine, for 304 * system calls and debug traps through their respective jump tables. 305 */ 306ENTRY(system_call) 307 setup_frame_reg 308#if !defined(CONFIG_CPU_SH2) 309 mov.l 1f, r9 310 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 311#endif 312 313 mov #OFF_TRA, r10 314 add r15, r10 315 mov.l r8, @r10 ! set TRA value to tra 316 317 /* 318 * Check the trap type 319 */ 320 mov #((0x20 << 2) - 1), r9 321 cmp/hi r9, r8 322 bt/s debug_trap ! it's a debug trap.. 323 nop 324 325 TRACE_IRQS_ON 326 sti 327 328 ! 329 get_current_thread_info r8, r10 330 mov.l @(TI_FLAGS,r8), r8 331 mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10 332 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9 333 tst r10, r8 334 shll8 r9 335 bf syscall_trace_entry 336 tst r9, r8 337 bf syscall_trace_entry 338 ! 339 mov.l 2f, r8 ! Number of syscalls 340 cmp/hs r8, r3 341 bt syscall_badsys 342 ! 343syscall_call: 344 shll2 r3 ! x4 345 mov.l 3f, r8 ! Load the address of sys_call_table 346 add r8, r3 347 mov.l @r3, r8 348 jsr @r8 ! jump to specific syscall handler 349 nop 350 mov.l @(OFF_R0,r15), r12 ! save r0 351 mov.l r0, @(OFF_R0,r15) ! save the return value 352 ! 353syscall_exit: 354 cli 355 TRACE_IRQS_OFF 356 ! 357 get_current_thread_info r8, r0 358 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 359 tst #(_TIF_ALLWORK_MASK & 0xff), r0 360 mov #(_TIF_ALLWORK_MASK >> 8), r1 361 bf syscall_exit_work 362 shlr8 r0 363 tst r0, r1 364 bf syscall_exit_work 365 bra __restore_all 366 nop 367 .align 2 368#if !defined(CONFIG_CPU_SH2) 3691: .long TRA 370#endif 3712: .long NR_syscalls 3723: .long sys_call_table 3737: .long do_syscall_trace_enter 3748: .long do_syscall_trace_leave 375